I thought I’d continue from my last blog piece talking about heavy current injection earth testing. By talking about a key application where it can potentially deliver much better results than the modern CDEGS approach. Therefore, on your earthing arrangements.
Many industrial sites built in the 1950s and 60s as industrialisation grew. This, in line with the expansion of the electrical grid. Led to a huge program of electrical substation construction around the world. What this means is that some of us own the responsibility of managing sites with ageing transformers, assets and equipment. Thus the design to obsolete standards? Therefore to know what hazard this presents today, is simply unknown.
We’ve already spoken about the changes in modern earthing standards in other articles:
Early Earthing Arrangements
So, it’s clear that these legacy site earthing arrangements won’t comply with modern standards.
Often, detailed construction information either wasn’t documented or has been lost or destroyed through expansion, acquisition etc. So, for these sites, especially in built-up areas. It’s challenging to build an accurate CDEGS model. Also, which determines whether the site’s earth system is keeping the people that work there safe.
Most of our blog pieces talk about the advantages of CDEGS and other modern computational tools for designing earthing arrangements. However, the computational approach relies on the quality of input data – i.e. garbage in = garbage out. We need to measure the local soil resistivity, and we need accurate drawings of the earth electrode from the site. Sometimes it’s just not possible to track down this sort of information. Hence, my blog title today – How do I know what’s happening with my ageing earthing arrangements.
So, for these sites, in particular. Using a planned maintenance outage for substantial current injection earth resistance measurements is an absolute no-brainer. Modern measurement techniques allow us to measure the actual earth resistance of the site directly. Also, as well as directly measuring step and touch voltages. Therefore, without the in-depth data gathering exercise required to build a CDEGS model. This information used to determine if the site presents a safe electrical environment for the people working there. So, If the measurements identify hazardous areas. Then, a small, focussed, design task performed. Rather than developing an exhaustively accurate model for an entire site.
This measurement process equally applies to substations in built-up areas where traditional fall-of-potential measurements are impractical.
Your Uncertainty about the Safety of Your People
So, if you want to get rid of the uncertainty surrounding whether the people working in and around your substations are safe, or a survey of your current Earthing Arrangements, then get in touch.